The present disclosure relates to the field of medical instruments and in particular, although not exclusively, to electrosurgical instruments. The present disclosure also relates to drive circuits and methods for driving such medical instruments. Additionally, the present disclosure is directed to lockout mechanisms, user interfaces, initialization techniques, and battery power conservation circuits and methods for such medical instruments.
Many surgical procedures require cutting or ligating blood vessels or other internal tissue. Many surgical procedures are performed using minimally invasive techniques where a handheld instrument is used by the surgeon to perform the cutting or ligating. Conventional hand-held electrosurgical instruments are generally large and bulky and require large power supplies and control electronics that are connected to the instrument through an electrical supply line.
Conventional corded electrosurgical instruments are large in size, have large power supplies and control electronics, and take up a lot of space in the operating room. Corded electrosurgical instruments are particularly cumbersome and difficult to use during a surgical procedure in part due to tethering of the hand-held electrosurgical instrument to the power supply and control electronics and the potential for cord entanglement. Some of these deficiencies have been overcome by providing battery powered hand-held electrosurgical instruments in which the power and control electronics are mounted within the instrument itself, such as within the handle of the instrument, to reduce the size of the electrosurgical instrument and make such instruments easier to use during surgical procedures.
Electrosurgical medical instruments generally include an end effector having an electrical contact, a radio frequency (RF) generation circuit for generating an RF drive signal and to provide the RF drive signal to the at least one electrical contact where the RF generation circuit also includes a resonant circuit. The RF circuit includes circuitry to generate a cyclically varying signal, such as a square wave signal, from a direct current (DC) energy source and the resonant circuit is configured to receive the cyclically varying signal from the switching circuitry. The DC energy source is generally provided by one or more batteries that can be mounted in a handle portion of the housing of the instrument, for example.
The design of battery powered hand-held electrosurgical instruments requires the electronics in the power supply and RF amplifier sections to have the highest efficiency possible in order to minimize the heat rejected into the relatively small handheld package. Increased efficiency also improves the storage and operational life of the battery. Increased efficiency also minimizes the size of the required battery or extends the life of a battery of a given size. Thus, there is a need for battery powered hand-held electrosurgical instruments having higher efficiency power supply and RF amplifier sections.